//---------------------------------------------------------------------------
// @function:
// CPhysicalComputeScalar::PrsDerive
//
// @doc:
// Derive rewindability
//
//---------------------------------------------------------------------------
CRewindabilitySpec *
CPhysicalComputeScalar::PrsDerive
(
IMemoryPool *pmp,
CExpressionHandle &exprhdl
)
const
{
CDrvdPropScalar *pdpscalar = exprhdl.Pdpscalar(1 /*ulChildIndex*/);
if (pdpscalar->FHasNonScalarFunction() || IMDFunction::EfsVolatile == pdpscalar->Pfp()->Efs())
{
// ComputeScalar is not rewindable if it has non-scalar/volatile functions in project list
return GPOS_NEW(pmp) CRewindabilitySpec(CRewindabilitySpec::ErtNone /*ert*/);
}
return PrsDerivePassThruOuter(exprhdl);
}
//---------------------------------------------------------------------------
// @function:
// CPhysicalComputeScalar::PdsRequired
//
// @doc:
// Compute required distribution of the n-th child
//
//---------------------------------------------------------------------------
CDistributionSpec *
CPhysicalComputeScalar::PdsRequired
(
IMemoryPool *pmp,
CExpressionHandle &exprhdl,
CDistributionSpec *pdsRequired,
ULONG ulChildIndex,
DrgPdp *, // pdrgpdpCtxt
ULONG ulOptReq
)
const
{
GPOS_ASSERT(0 == ulChildIndex);
GPOS_ASSERT(2 > ulOptReq);
// check if master-only/replicated distribution needs to be requested
CDistributionSpec *pds = PdsMasterOnlyOrReplicated(pmp, exprhdl, pdsRequired, ulChildIndex, ulOptReq);
if (NULL != pds)
{
return pds;
}
CDrvdPropScalar *pdpscalar = exprhdl.Pdpscalar(1 /*ulChildIndex*/);
// if a Project operator has a call to a set function, passing a Random distribution through this
// Project may have the effect of not distributing the results of the set function to all nodes,
// but only to the nodes on which first child of the Project is distributed.
// to avoid that, we don't push the distribution requirement in this case and thus, for a random
// distribution, the result of the set function is spread uniformly over all nodes
if (pdpscalar->FHasNonScalarFunction())
{
return GPOS_NEW(pmp) CDistributionSpecAny();
}
// if required distribution uses any defined column, it has to be enforced on top of ComputeScalar,
// in this case, we request Any distribution from the child
CDistributionSpec::EDistributionType edtRequired = pdsRequired->Edt();
if (CDistributionSpec::EdtHashed == edtRequired)
{
CDistributionSpecHashed *pdshashed = CDistributionSpecHashed::PdsConvert(pdsRequired);
CColRefSet *pcrs = pdshashed->PcrsUsed(m_pmp);
BOOL fUsesDefinedCols = FUnaryUsesDefinedColumns(pcrs, exprhdl);
pcrs->Release();
if (fUsesDefinedCols)
{
return GPOS_NEW(pmp) CDistributionSpecAny();
}
}
if (CDistributionSpec::EdtRouted == edtRequired)
{
CDistributionSpecRouted *pdsrouted = CDistributionSpecRouted::PdsConvert(pdsRequired);
CColRefSet *pcrs = GPOS_NEW(m_pmp) CColRefSet(m_pmp);
pcrs->Include(pdsrouted->Pcr());
BOOL fUsesDefinedCols = FUnaryUsesDefinedColumns(pcrs, exprhdl);
pcrs->Release();
if (fUsesDefinedCols)
{
return GPOS_NEW(pmp) CDistributionSpecAny();
}
}
if (0 == ulOptReq)
{
// Req0: required distribution will be enforced on top of ComputeScalar
return GPOS_NEW(pmp) CDistributionSpecAny();
}
// Req1: required distribution will be enforced on top of ComputeScalar's child
return PdsPassThru(pmp, exprhdl, pdsRequired, ulChildIndex);
}